Detection of Aerosolized Anabaenopeptins from Cyanobacterial Harmful Algal Blooms in Atmospheric Particulate Matter

Cyanobacterial harmful algal blooms (cHABs) can produce bioactive compounds that can pose a public health risk, including anabaenopeptins (APs), a family of metabolites comprised of six amino acids in a five-membered cyclic structure shown to inhibit several important enzymes. Only a few studies have quantified APs in water, and no studies have measured APs in the atmosphere. The limited waterborne measurements indicate that APs are frequently present at concentrations higher than other potent toxins and metabolites produced by cyanobacteria. Herein, this study quantifies concentrations of the four abundant AP congeners (AP-B, AP-F, AP-A, and Osc-Y) in water samples and atmospheric aerosol samples from around Grand Lake St. Marys (GLSM), Ohio, in 2019 and 2022. In 2019, the total AP concentration in GLSM water was 130 ± 20 μg/L, dominated by the AP-B congener. In 2022, the total water concentration of APs was 70 ± 20 μg/L and was instead dominated by AP-F. Particulate matter (PM) AP concentrations up to 48 pg/m³ were detected in 2019, 3.7 times higher than microcystin toxins (13 pg/m³) sampled at the same time. Aerosolization of extracellular versus intracellular APs was explored using raw and lysed GLSM water samples. Water samples lysed via freeze–thaw cycles showed up to a 100× increase in aerosolized AP concentrations. Measurements of aerosolized APs in the ambient atmosphere and the connection to water concentrations demonstrate the need for further research on inhalation exposure to airborne APs and evaluation of potential impacts on public health.